Iodine and Starch Experiment | Iodine Experiment | Starch Experiment | Science experiments for kids



Iodine and Starch Experiment | Iodine Experiment | Starch Experiment | Science experiments for kids

Simple and easy experiment to demonstrate the iodine with starch reaction!

For this test you will need:
• Two test tubes
• Soluble starch powder
• Iodine solution
• Water
• Dropper
Procedure:
• Put some starch powder into a test tube and fill the test tube with water.
• Mix the starch in the test tube well until the starch dissolves in the water.
• Fill the other test tube with normal water.
• Place both the test tubes in a test tube stand.
• Using a dropper take iodine solution.
• Put some drops in each test tube.
• Observe that the test tube with starch solution turns to purple black color.
• The other test tube with normal water retains the color of iodine i.e orange or yellow.
Explanation:
Starch is a mixture of amylose and amylopectin, which are different forms of glucose/starch.
Amylose in starch is responsible for the formation of a deep blue black color.
Amylase is long polymer chains of glucose units connected by an alpha acetal linkage and looks much like a coiled spring.
However iodine is a potassium iodide reagent and it is not very soluble in water.
So, iodine is prepared by dissolving it in water in an aqueous solution of potassium iodide. This results in a linear tri-iodide ion (I3−) complex in iodine which is soluble.
This tri-iodide ion (I3−) slips into the coil of the starch causing an intense or deep blue-black color.

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